One of the investigations was launched in 2015, after several recruits completed boot camp and came forward to superiors to complain

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Newly sworn in US Marines receive the Eagle, Globe and Anchor pin during a dawn ceremony marking their transition from a recruit to a Marine January 8, 2011 at the Marine Corps Recruit Depot on Parris Island, South Carolina. The center is under investigation over hazing and abusing accusations.

Investigations into alleged hazing and maltreatment of recruits have found evidence of a toxic command climate at the Marines' training center at Parris Island, South Carolina, going back more than two years, according to Marine documents reviewed Wednesday by NBC News.

Detailed results of the investigations — one of them reviewing the alleged suicide of a new recruit in March — have been forwarded to prosecutors for "drafting of charges as warranted," according to one of the documents.

The Marine Corps said last week that the inquiries focus on three platoons of the Third Recruit Training Battalion. It said 20 training personnel had been "identified for possible military justice or administrative action," confirming a report by NBC News that the personnel — a mix of drill instructors and officers — were directly involved in hazing or had ignored evidence that it was going on.